Well, the plot could involve Hiccup discovering his new role as the Prince of Dragons and having to deal with the responsibilities that come with it. He might have to unite different dragon tribes under his leadership and face challenges from dragon hunters who see his new position as a threat.
Perhaps the fanfic could be about Hiccup's journey to fully understand his connection to the dragons as a prince. He could go on quests to find ancient dragon artifacts that will help him in his role. Along the way, he'd make new friends and enemies, and his relationship with Toothless would evolve in unexpected ways as they both adapt to his new status.
In this fanfic, it could start with Hiccup being chosen as the Prince of Dragons in a mysterious ceremony. Then, he has to learn the ways of the dragons on a much deeper level, like understanding their complex social hierarchies. He may also be tasked with protecting a hidden dragon sanctuary that holds the key to the dragons' future, all while trying to keep his new identity a secret from the people of Berk who might not understand.
Chapter 324, "Enrollment", is the clearest early answer because it turns Zhou Xu's situation into a concrete plot event. The chapter turns that into something concrete by moving from An ancient and majestic building, striped red and white, gathered the...
Chapter 262, "Flash Change Quartet Speaks Out for Jiang Li", is the clearest early answer because it turns Sister Chen's situation into a concrete plot event. It opens with Wen Jiaojiao couldn't stand it anymore and immediately logged onto... and closes on Your manager restricts that as well?.
Chapter 229, "He's Actually Brother Liu, the Watermelon Seller?!", is the clearest early answer because it turns Huo Ziyang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Huo Ziyang's face had already turned deathly pale.
Chapter 314, "The teacher will surely cultivate you into a new music star!", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event.
Chapter 464, "Is it Lingzhi?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Li's calculations were indeed correct.
Chapter 376, "I'm Just Afraid You Don't Need Me Anymore", is the clearest early answer because it turns Gu Yu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The phone call fell into a long silence.
Chapter 353, "He's Lying!", is the clearest early answer because it turns Liu Suqing's situation into a concrete plot event. The chapter turns that into something concrete by moving from The three of them turned their heads together.
Chapter 364, "This is the gift our master sends you for the first meeting", is the clearest early answer because it turns Vajra Relics's situation into a concrete plot event.
Chapter 260, "Did You Take All These People Down?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Yan Dabiao, who deeply felt the sting of deception, flew into a rage...
Chapter 143, "How about Grandma introducing a girlfriend to you?", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. Early on, Is there really such delicious fish soup in the world?.